diff --git a/acl.go b/acl.go
index c9c9665..3e8a5bd 100644
--- a/acl.go
+++ b/acl.go
@@ -51,7 +51,7 @@ func (ext *ACLExt) Process(ctx *Context, node *Node, source NodeID, signal Signa
     var changes Changes = nil
     info, waiting := ext.Pending[response.ResponseID()]
     if waiting == true {
-      changes = changes.Add("response_processed")
+      changes.Add(ACLExtType, "pending")
       delete(ext.Pending, response.ResponseID())
       if response.ID() != info.Timeout {
         err := node.DequeueSignal(info.Timeout)
@@ -78,26 +78,26 @@ func (ext *ACLExt) Process(ctx *Context, node *Node, source NodeID, signal Signa
           }
         } else {
           if ext.Policies[policy_index].ContinueAllows(ctx, acl_info, response) == Allow {
+            changes.Add(ACLExtType, "pending_acls")
             delete(ext.PendingACLs, info.ID)
             ctx.Log.Logf("acl", "Request delayed allow")
             messages = messages.Add(ctx, acl_info.Source, node, nil, NewSuccessSignal(info.ID))
-            changes = changes.Add("acl_passed")
             err := node.DequeueSignal(acl_info.TimeoutID)
             if err != nil {
               ctx.Log.Logf("acl", "acl proxy timeout dequeue error: %s", err)
             }
           } else if acl_info.Counter == 0 {
+            changes.Add(ACLExtType, "pending_acls")
             delete(ext.PendingACLs, info.ID)
             ctx.Log.Logf("acl", "Request delayed deny")
             messages = messages.Add(ctx, acl_info.Source, node, nil, NewErrorSignal(info.ID, "acl_denied"))
-            changes = changes.Add("acl_blocked")
             err := node.DequeueSignal(acl_info.TimeoutID)
             if err != nil {
               ctx.Log.Logf("acl", "acl proxy timeout dequeue error: %s", err)
             }
           } else {
             node.PendingACLs[info.ID] = acl_info
-            changes = changes.Add("acl_processed")
+            changes.Add(ACLExtType, "pending_acls")
           }
         }
       }
@@ -136,7 +136,7 @@ func (ext *ACLExt) Process(ctx *Context, node *Node, source NodeID, signal Signa
       messages = messages.Add(ctx, source, node, nil, NewErrorSignal(sig.Id, "acl_denied"))
     } else if acl_messages != nil {
       ctx.Log.Logf("acl", "Request pending")
-      changes = changes.Add("acl_pending")
+      changes.Add(ACLExtType, "pending")
       total_messages := 0
       // TODO: reasonable timeout/configurable
       timeout_time := time.Now().Add(time.Second)
@@ -175,9 +175,9 @@ func (ext *ACLExt) Process(ctx *Context, node *Node, source NodeID, signal Signa
     acl_info, exists := ext.PendingACLs[sig.ReqID]
     if exists == true {
       delete(ext.PendingACLs, sig.ReqID)
+      changes.Add(ACLExtType, "pending_acls")
       ctx.Log.Logf("acl", "Request timeout deny")
       messages = messages.Add(ctx, acl_info.Source, node, nil, NewErrorSignal(sig.ReqID, "acl_timeout"))
-      changes = changes.Add("acl_timeout")
       err := node.DequeueSignal(acl_info.TimeoutID)
       if err != nil {
         ctx.Log.Logf("acl", "acl proxy timeout dequeue error: %s", err)
diff --git a/context.go b/context.go
index 63949f1..b6b7f54 100644
--- a/context.go
+++ b/context.go
@@ -315,6 +315,7 @@ func (ctx *Context) getNode(id NodeID) (*Node, error) {
 // Route Messages to dest. Currently only local context routing is supported
 func (ctx *Context) Send(messages Messages) error {
   for _, msg := range(messages) {
+    ctx.Log.Logf("signal", "Sending %s -> %+v", msg.Dest, msg)
     if msg.Dest == ZeroID {
       panic("Can't send to null ID")
     }
@@ -480,7 +481,7 @@ func NewContext(db * badger.DB, log Logger) (*Context, error) {
     return nil, err
   }
 
-  err = ctx.RegisterType(reflect.TypeOf(Changes{}), ChangesSerialized, SerializeTypeStub, SerializeSlice, DeserializeTypeStub[Changes], DeserializeSlice)
+  err = ctx.RegisterType(reflect.TypeOf(Changes{}), ChangesSerialized, SerializeTypeStub, SerializeMap, DeserializeTypeStub[Changes], DeserializeMap)
   if err != nil {
     return nil, err
   }
@@ -613,6 +614,11 @@ func NewContext(db * badger.DB, log Logger) (*Context, error) {
     return nil, err
   }
 
+  err = ctx.RegisterPolicy(reflect.TypeOf(ParentOfPolicy{}), ParentOfPolicyType)
+  if err != nil {
+    return nil, err
+  }
+
   err = ctx.RegisterPolicy(reflect.TypeOf(MemberOfPolicy{}), MemberOfPolicyType)
   if err != nil {
     return nil, err
diff --git a/event.go b/event.go
index b9aa399..bca6fd5 100644
--- a/event.go
+++ b/event.go
@@ -5,6 +5,40 @@ import (
   "fmt"
 )
 
+type ParentOfPolicy struct {
+  PolicyHeader
+  Policy Tree
+}
+
+func NewParentOfPolicy(policy Tree) *ParentOfPolicy {
+  return &ParentOfPolicy{
+    PolicyHeader: NewPolicyHeader(),
+    Policy: policy,
+  }
+}
+
+func (policy ParentOfPolicy) Allows(ctx *Context, principal_id NodeID, action Tree, node *Node)(Messages, RuleResult) {
+  event_ext, err := GetExt[*EventExt](node, EventExtType)
+  if err != nil {
+    ctx.Log.Logf("event", "ParentOfPolicy, node not event %s", node.ID)
+    return nil, Deny
+  }
+
+  if event_ext.Parent == principal_id {
+    return nil, policy.Policy.Allows(action)
+  }
+
+  return nil, Deny
+}
+
+func (policy ParentOfPolicy) ContinueAllows(ctx *Context, current PendingACL, signal Signal) RuleResult {
+  return Deny
+}
+
+var DefaultEventPolicy = NewParentOfPolicy(Tree{
+  SerializedType(EventControlSignalType): nil,
+})
+
 type EventExt struct {
   Name string `gv:"name"`
   State string `gv:"state"`
@@ -148,3 +182,21 @@ func (ext *TestEventExt) Process(ctx *Context, node *Node, source NodeID, signal
 
   return messages, changes
 }
+
+type TransitionValidation struct {
+  ToState string
+}
+
+func(ext *EventExt) ValidateEventCommand(signal *EventControlSignal, commands map[string]map[string]string) (string, *ErrorSignal) {
+  transitions, command_mapped := commands[signal.Command]
+  if command_mapped == false {
+    return "", NewErrorSignal(signal.Id, "unknown command %s", signal.Command)
+  } else {
+    new_state, valid_transition := transitions[ext.State]
+    if valid_transition == false {
+      return "", NewErrorSignal(signal.Id, "invalid command state %s(%s)", signal.Command, ext.State)
+    } else {
+      return new_state, nil
+    }
+  }
+}
diff --git a/gql.go b/gql.go
index c7a6c9a..239c8f2 100644
--- a/gql.go
+++ b/gql.go
@@ -1562,6 +1562,7 @@ type GQLExt struct {
   resolver_response map[uuid.UUID]chan Signal
   resolver_response_lock sync.RWMutex
 
+  State string `gv:"state"`
   TLSKey []byte `gv:"tls_key"`
   TLSCert []byte `gv:"tls_cert"`
   Listen string `gv:"listen"`
@@ -1692,7 +1693,8 @@ func (ext *GQLExt) Process(ctx *Context, node *Node, source NodeID, signal Signa
     ctx.Log.Logf("gql", "starting gql server %s", node.ID)
     err := ext.StartGQLServer(ctx, node)
     if err == nil {
-      changes = changes.Add("server_started")
+      ctx.Log.Logf("gql", "started gql server on %s", ext.Listen)
+      changes.Add(GQLExtType, "state")
     } else {
       ctx.Log.Logf("gql", "GQL_RESTART_ERROR: %s", err)
     }
@@ -1873,6 +1875,7 @@ func (ext *GQLExt) StartGQLServer(ctx *Context, node *Node) error {
 
   ext.tcp_listener = l
   ext.http_server = http_server
+  ext.State = "running"
   return nil
 }
 
@@ -1884,5 +1887,6 @@ func (ext *GQLExt) StopGQLServer() error {
   ext.http_done.Wait()
   ext.tcp_listener = nil
   ext.http_server = nil
+  ext.State = "stopped"
   return nil
 }
diff --git a/gql_test.go b/gql_test.go
index fff7759..d63d13e 100644
--- a/gql_test.go
+++ b/gql_test.go
@@ -43,7 +43,7 @@ func TestGQLAuth(t *testing.T) {
 }
 
 func TestGQLServer(t *testing.T) {
-  ctx := logTestContext(t, []string{"test", "deserialize_types", "serialize_types", "gqlws"})
+  ctx := logTestContext(t, []string{"test", "deserialize_types", "serialize_types", "gqlws", "gql"})
 
   TestNodeType := NewNodeType("TEST")
   err := ctx.RegisterNodeType(TestNodeType, []ExtType{LockableExtType})
@@ -218,7 +218,9 @@ func TestGQLServer(t *testing.T) {
     ctx.Log.Logf("test", "SUB: %s", resp[:n])
 
     msgs := Messages{}
-    msgs = msgs.Add(ctx, gql.ID, gql, nil, NewStatusSignal(gql.ID, Changes{"test_status"}))
+    test_changes := Changes{}
+    test_changes.Add(GQLExtType, "state")
+    msgs = msgs.Add(ctx, gql.ID, gql, nil, NewStatusSignal(gql.ID, test_changes))
     err = ctx.Send(msgs)
     fatalErr(t, err)
 
diff --git a/group.go b/group.go
index b5f12b5..b865e20 100644
--- a/group.go
+++ b/group.go
@@ -240,7 +240,7 @@ func (ext *GroupExt) Process(ctx *Context, node *Node, source NodeID, signal Sig
         ext.SubGroups[sig.SubGroup] = sub_group
 
         messages = messages.Add(ctx, source, node, nil, NewSuccessSignal(sig.Id))
-        changes = changes.Add("member_added")
+        changes.Add(GroupExtType, "sub_groups")
       }
     }
 
@@ -257,7 +257,7 @@ func (ext *GroupExt) Process(ctx *Context, node *Node, source NodeID, signal Sig
         ext.SubGroups[sig.SubGroup] = sub_group
 
         messages = messages.Add(ctx, source, node, nil, NewSuccessSignal(sig.Id))
-        changes = changes.Add("member_removed")
+        changes.Add(GroupExtType, "sub_groups")
       }
     }
 
@@ -268,7 +268,7 @@ func (ext *GroupExt) Process(ctx *Context, node *Node, source NodeID, signal Sig
     } else {
       ext.SubGroups[sig.Name] = []NodeID{}
 
-      changes = changes.Add("subgroup_added")
+      changes.Add(GroupExtType, "sub_groups")
       messages = messages.Add(ctx, source, node, nil, NewSuccessSignal(sig.Id))
     }
   case *RemoveSubGroupSignal:
@@ -278,7 +278,7 @@ func (ext *GroupExt) Process(ctx *Context, node *Node, source NodeID, signal Sig
     } else {
       delete(ext.SubGroups, sig.Name)
 
-      changes = changes.Add("subgroup_removed")
+      changes.Add(GroupExtType, "sub_groups")
       messages = messages.Add(ctx, source, node, nil, NewSuccessSignal(sig.Id))
     }
   }
diff --git a/lockable.go b/lockable.go
index cefa010..b8f0228 100644
--- a/lockable.go
+++ b/lockable.go
@@ -113,7 +113,7 @@ func (ext *LockableExt) HandleLinkSignal(ctx *Context, node *Node, source NodeID
           ext.Requirements = map[NodeID]ReqState{}
         }
         ext.Requirements[signal.NodeID] = Unlocked
-        changes = changes.Add("requirement_added")
+        changes.Add(LockableExtType, "requirements")
         messages = messages.Add(ctx, source, node, nil, NewSuccessSignal(signal.ID()))
       }
     case "remove":
@@ -122,7 +122,7 @@ func (ext *LockableExt) HandleLinkSignal(ctx *Context, node *Node, source NodeID
         messages = messages.Add(ctx, source, node, nil, NewErrorSignal(signal.ID(), "can't link: not_requirement"))
       } else {
         delete(ext.Requirements, signal.NodeID)
-        changes = changes.Add("requirement_removed")
+        changes.Add(LockableExtType, "requirements")
         messages = messages.Add(ctx, source, node, nil, NewSuccessSignal(signal.ID()))
       }
     default:
@@ -163,10 +163,10 @@ func (ext *LockableExt) HandleSuccessSignal(ctx *Context, node *Node, source Nod
             ctx.Log.Logf("lockable", "WHOLE LOCK: %s - %s - %+v", node.ID, ext.PendingID, ext.PendingOwner)
             ext.State = Locked
             ext.Owner = ext.PendingOwner
-            changes = changes.Add("locked")
+            changes.Add(LockableExtType, "state", "owner", "requirements")
             messages = messages.Add(ctx, *ext.Owner, node, nil, NewSuccessSignal(ext.PendingID))
           } else {
-            changes = changes.Add("partial_lock")
+            changes.Add(LockableExtType, "requirements")
             ctx.Log.Logf("lockable", "PARTIAL LOCK: %s - %d/%d", node.ID, locked, len(ext.Requirements))
           }
         case AbortingLock:
@@ -199,15 +199,15 @@ func (ext *LockableExt) HandleSuccessSignal(ctx *Context, node *Node, source Nod
             previous_owner := *ext.Owner
             ext.Owner = ext.PendingOwner
             ext.ReqID = nil
-            changes = changes.Add("unlocked")
+            changes.Add(LockableExtType, "state", "owner", "req_id")
             messages = messages.Add(ctx, previous_owner, node, nil, NewSuccessSignal(ext.PendingID))
           } else if old_state == AbortingLock {
-            changes = changes.Add("lock_aborted")
+            changes.Add(LockableExtType, "state", "pending_owner")
             messages = messages.Add(ctx, *ext.PendingOwner, node, nil, NewErrorSignal(*ext.ReqID, "not_unlocked"))
             ext.PendingOwner = ext.Owner
           }
         } else {
-          changes = changes.Add("partial_unlock")
+          changes.Add(LockableExtType, "state")
           ctx.Log.Logf("lockable", "PARTIAL UNLOCK: %s - %d/%d", node.ID, unlocked, len(ext.Requirements))
         }
       }
@@ -231,7 +231,7 @@ func (ext *LockableExt) HandleLockSignal(ctx *Context, node *Node, source NodeID
         new_owner := source
         ext.PendingOwner = &new_owner
         ext.Owner = &new_owner
-        changes = changes.Add("locked")
+        changes.Add(LockableExtType, "state", "pending_owner", "owner")
         messages = messages.Add(ctx, new_owner, node, nil, NewSuccessSignal(signal.ID()))
       } else {
         ext.State = Locking
@@ -240,7 +240,7 @@ func (ext *LockableExt) HandleLockSignal(ctx *Context, node *Node, source NodeID
         new_owner := source
         ext.PendingOwner = &new_owner
         ext.PendingID = signal.ID()
-        changes = changes.Add("locking")
+        changes.Add(LockableExtType, "state", "req_id", "pending_owner", "pending_id")
         for id, state := range(ext.Requirements) {
           if state != Unlocked {
             ctx.Log.Logf("lockable", "REQ_NOT_UNLOCKED_WHEN_LOCKING")
@@ -264,7 +264,7 @@ func (ext *LockableExt) HandleLockSignal(ctx *Context, node *Node, source NodeID
         new_owner := source
         ext.PendingOwner = nil
         ext.Owner = nil
-        changes = changes.Add("unlocked")
+        changes.Add(LockableExtType, "state", "pending_owner", "owner")
         messages = messages.Add(ctx, new_owner, node, nil, NewSuccessSignal(signal.ID()))
       } else if source == *ext.Owner {
         ext.State = Unlocking
@@ -272,7 +272,7 @@ func (ext *LockableExt) HandleLockSignal(ctx *Context, node *Node, source NodeID
         ext.ReqID = &id
         ext.PendingOwner = nil
         ext.PendingID = signal.ID()
-        changes = changes.Add("unlocking")
+        changes.Add(LockableExtType, "state", "pending_owner", "pending_id", "req_id")
         for id, state := range(ext.Requirements) {
           if state != Locked {
             ctx.Log.Logf("lockable", "REQ_NOT_LOCKED_WHEN_UNLOCKING")
@@ -405,7 +405,7 @@ func (policy RequirementOfPolicy) ContinueAllows(ctx *Context, current PendingAC
     return Deny
   }
 
-  for req, _ := range(requirements) {
+  for req := range(requirements) {
     if req == current.Principal {
       return policy.NodeRules[sig.NodeID].Allows(current.Action)
     }
diff --git a/node.go b/node.go
index f6e01f3..0291cd4 100644
--- a/node.go
+++ b/node.go
@@ -46,10 +46,18 @@ func RandID() NodeID {
   return NodeID(uuid.New())
 }
 
-type Changes []string
+type Changes map[ExtType][]string
 
-func (changes Changes) Add(detail string) Changes {
-  return append(changes, detail)
+func (changes *Changes) Add(ext ExtType, fields ...string) {
+  if *changes == nil {
+    *changes = Changes{}
+  }
+  current, exists := (*changes)[ext]
+  if exists == false {
+    current = []string{}
+  }
+  current = append(current, fields...)
+  (*changes)[ext] = current
 }
 
 // Extensions are data attached to nodes that process signals
@@ -533,14 +541,18 @@ func (node *Node) Process(ctx *Context, source NodeID, signal Signal) error {
   for ext_type, ext := range(node.Extensions) {
     ctx.Log.Logf("node_process", "PROCESSING_EXTENSION: %s/%s", node.ID, ext_type)
     ext_messages, ext_changes := ext.Process(ctx, node, source, signal)
+    ctx.Log.Logf("gql", "%s changes %+v", reflect.TypeOf(ext), ext_changes)
     if len(ext_messages) != 0 {
       messages = append(messages, ext_messages...)
     }
 
     if len(ext_changes) != 0 {
-      changes = append(changes, ext_changes...)
+      for ext, change_list := range(ext_changes) {
+        changes[ext] = append(changes[ext], change_list...)
+      }
     }
   }
+  ctx.Log.Logf("gql", "changes after process %+v", changes)
 
   if len(messages) != 0 {
     send_err := ctx.Send(messages)
diff --git a/node_test.go b/node_test.go
index e2e51c4..69087d5 100644
--- a/node_test.go
+++ b/node_test.go
@@ -19,7 +19,11 @@ func TestNodeDB(t *testing.T) {
   fatalErr(t, err)
 
   _, err = WaitForSignal(node_listener.Chan, 10*time.Millisecond, func(sig *StatusSignal) bool {
-    return slices.Contains(sig.Changes, "started") && sig.Source == node.ID
+    gql_changes, has_gql := sig.Changes[GQLExtType]
+    if has_gql == true {
+      return slices.Contains(gql_changes, "state") && sig.Source == node.ID
+    }
+    return false
   })
 
   msgs := Messages{}
diff --git a/serialize.go b/serialize.go
index 4927b0a..e0020f7 100644
--- a/serialize.go
+++ b/serialize.go
@@ -59,6 +59,12 @@ func (t PolicyType) String() string {
   return fmt.Sprintf("0x%x", uint64(t))
 }
 
+type FieldTag SerializedType
+
+func (t FieldTag) String() string {
+  return fmt.Sprintf("0x%x", uint64(t))
+}
+
 type Chunk struct {
   Data []byte
   Next *Chunk
@@ -190,6 +196,10 @@ func NewPolicyType(name string) PolicyType {
   return PolicyType(Hash(PolicyTypeBase, name))
 }
 
+func NewFieldTag(tag_string string) FieldTag {
+  return FieldTag(Hash(FieldNameBase, tag_string))
+}
+
 func NewSerializedType(name string) SerializedType {
   return Hash(SerializedTypeBase, name)
 }
@@ -227,7 +237,8 @@ var (
   EventControlSignalType   = NewSignalType("EVENT_CONTORL")
   EventStateSignalType     = NewSignalType("VEX_MATCH_STATUS")
 
-  MemberOfPolicyType      = NewPolicyType("USER_OF")
+  MemberOfPolicyType      = NewPolicyType("MEMBER_OF")
+  ParentOfPolicyType      = NewPolicyType("PARENT_OF")
   RequirementOfPolicyType = NewPolicyType("REQUIEMENT_OF")
   PerNodePolicyType       = NewPolicyType("PER_NODE")
   AllNodesPolicyType      = NewPolicyType("ALL_NODES")
diff --git a/serialize_test.go b/serialize_test.go
index bf5b052..15796b4 100644
--- a/serialize_test.go
+++ b/serialize_test.go
@@ -119,8 +119,6 @@ func TestSerializeBasic(t *testing.T) {
 
   testSerialize[[]string](t, ctx, []string{"test_1", "test_2", "test_3"})
   testSerialize[test_slice](t, ctx, test_slice{"test_1", "test_2", "test_3"})
-
-  testSerialize[Changes](t, ctx, Changes{"change_1", "change_2", "change_3"})
 }
 
 type test struct {
diff --git a/signal.go b/signal.go
index c1b157f..c56190f 100644
--- a/signal.go
+++ b/signal.go
@@ -238,7 +238,7 @@ func (signal ErrorSignal) Permission() Tree {
     },
   }
 }
-func NewErrorSignal(req_id uuid.UUID, fmt_string string, args ...interface{}) Signal {
+func NewErrorSignal(req_id uuid.UUID, fmt_string string, args ...interface{}) *ErrorSignal {
   return &ErrorSignal{
     NewResponseHeader(req_id, Direct),
     fmt.Sprintf(fmt_string, args...),